Camshaftt gear for internal combustioin engines



April 30, 1957 J. GASSMANN 2,790,431 CAMSHAFT GEAR FOR INTERNAL COMBUSTION ENGINES Filed Nov. 18, 1955 V INVENTOR JOHANNES GASSMANN.

ATTORNEYS CAMSHAFT GEAR FOR INTERNAL COMBUSTION ENGINES Johannes Gassmann, Altbach, near Esslingen (Neckar), Germany, assignor to Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkheim, Germany The present invention deals with camshaft gears in internal combustion engines, and more particularly with a camshaft gear, the camshaft of which is driven by a driving shaft arranged at some distance from it.

In an internal combustion engine the distance between the centers of the camshaft and of the driving shaft is subjected to variations owing to the thermal expansion of the cylinder and the cylinder head.

A general object of the present invention is to provide for improvements avoiding the impairing eifects of the thermal expansion on the camshaft gear.

An essential feature of the present invention consists in the camshaft being driven by an intermediate shaft, which, on its part, is operated by a driven shaft, the dis tance between the centers of the camshaft and the intermediate shaft being kept constant by a rigid member, and the intermediate shaft being arranged so as to be positionable about the axis of the driving shaft. In this way it is possible to carry the driving shaft in a bearing rigidly arranged in the cylinder block, as well as the camshaft in a bearing rigidly arranged at the cylinder head, but yet to eliminate the effect of the thermal expansion.

Another feature of the present invention is to provide gear wheels for driving the intermediate shaft through the driving shaft, and a parallel crank gear for driving the camshaft through the intermediate shaft.

Another feature of the present invention consists in the intermediate shaft being carried in a positionable driving case mounted on the driving shaft and surrounding the gearing for driving the intermediate shaft.

According to another important feature of the present invention the said gearing along with its positionable case surrounding the same serves as a gear pump of the lubricating system of the internal combustion engine.

Further objects and features of the present invention will be apparent from the following description taken in connection with the accompanying drawings, in which Fig. 1 shows the left side elevational view of the camshaft drive illustrating an example of construction in accordance with the present invention;

Fig. 2 shows the longitudinal section through a parallel crank gear on the line 11-11 of Fig. 1; and

Fig. 3 shows a section through the positionable driving case on the line IlIIlI of Fig. 1.

In Figs. 1, 2 and 3 reference numeral 1 designates the crankcase, 2 the cylinder block and 3 the cylinder head of an internal combustion engine. In the crankcase 1 there is provided the crankshaft 4, and on the top of the cylinder head 3 the camshaft 5 solidly embedded or supported in a Well-known Way. An extension together with a gear wheel 6 is fastened to the end of the crankshaft 4 by means of a screw 7, while the gear wheel 6 is prevented from rotating relative to the crankshaft 4 by the use of a catch or spline. A second gear wheel 9 is mounted on a suitable intermediate shaft formed, for example, by two bearing journals on each side of the gear wheel 9, and is in meshing engagement with the gear wheel 6. The driving case 8 which encircles and supports the sec ted States Patent 6 0nd gear wheel 9 of the camshaft drive is also positionably supported on the extension of the crankshaft 4. Coaxial to the axis of this gear wheel 9 the tie rod 10 is supported on the driving case 8. With its top end the tie rod 10 is supported on the concentric section 5' of the camshaft 5 so as to be positionable about said section 5' and therewith. about camshaft 5. Due to the tie rod 10 the positionable driving case 8 is held in its position just defined by the thermal expansion of the cylinder block 2 and the cylinder head 3. At the gear wheel 9 there are provided the two crank pins 11 and 12, which are connected with the corresponding crank pins 15' and 16 of the camshaft by way of the two connecting rods 13 and 14. This parallel crankshaft drive always operates unobjectionably without any jamming, because the tie rod It causes the distance between the centers of the parallel crankshaft drive, i. e., the distance between the axis of the camshaft 5 and section 5 and the axis of the intermediate shaft of the gear wheel 9 to be constant regardless of any expansion by heat in the block 2 and cylinder head 3, that is, of any variations in the distance between the centers of the crankshaft 4 and the camshaft 5. Thus, any variations in the distance between the crankshaft 4 and the camshaft 5 due to thermal expansion is compensated for by the turning movement of easing 8 and therewith of the lower end of tie rod 10 about the axis of the intermediate shaft or journal bearings of gear wheel 9, while the distance between the axis of the intermediate shaft of gear wheel 9 and the camshaft 5 remains constant since the tie rod is spaced at a sufficiently large distance from the block and cylinder head to be substantially unaffected by the thermal expansions in the block and cylinder head. In order to avoid dead centers in transmitting power to the camshaft 5, two parallel crank gears are provided, which are staggered about to each other.

The gear wheels 6 and 9 along with the case 25 are designed so as to embody an oil pump for the lubricating system of the internal combustion engine. The oil flow is indicated by the arrows 1'7 and 18. With engines of the usual construction the gear wheels of the camshaft gear are hardly adapted to act as an additional oil pump, because the large diameter of the gear wheels-as the result of the relatively wide distance between the crankshaft and the camshafb-would cause too much oil to be delivered, and along with it the pump case would become too heavy. The camshaft gear according to the invention involves the advantage that the designer will not be bound to a given wide distance of the centers in proportioning the gear wheels, but he can keep it as small as possible in regard to the most favorable power transmission and the required output of the oil pump.

Other modifications may be resorted to without departing from the spirit of the invention and its scope as defined by the appended claims.

What is claimed is:

1. In an internal combustion engine an engine crankcase, a driving shaft, an intermediate shaft, means for supporting the intermediate shaft, said supporting means being positionable in relation to the engine crankcase, means for driving the intermediate shaft by the driving shaft, a camshaft, a rigid link member positionable about the axis of the camshaft and about the axis of the intermediate shaft and providing a constant distance between said two axes, and means for driving the camshaft by the intermediate shaft.

2. In an internal combustion engine a driving shaft, an intermediate shaft arranged parallel to the driving shaft, means for supporting the intermediate shaft, saidsupporting means being positionable about the axis of the driving shaft, means for driving the intermediate shaft by the driving shaft, a camshaft, a rigid link member being positionable about the axis of the camshaft and about the axis of the intermediate shaft and providing a constant distance between both said axes, and means for driving the camshaft by the intermediate shaft.

3. In an internal combustion engine a driving shaft, an intermediate shaft arranged parallel to the driving shaft provided with at least one crank pin, means for supporting the intermediate shaft, said supporting means being positionable about the axis of the driving shaft, a gear wheel on the driving shaft, a gear wheel on the intermediate shaft, said gear wheels causing the intermediate shaft to be driven by the driving shaft, a camshaft provided with at least one crank pin, a rigid link member positionable about the axis of the camshaft and about the axis of the intermediate shaft providing a constant distance between both said axes, and at least one connecting rod, each between a crank pin of the intermediate shaft and of the camshaft, causing the camshaft to be driven by the intermediate shaft.

4. In an internal combustion engine a driving shaft, an intermediate shaft arranged parallel to the driving shaft and provided with two crank pins, means for supporting the intermediate shaft, said supporting means being positionably supported on the driving shaft, a gear wheel on the driving shaft, a gear wheel on the intermediate shaft, said gear wheels meshing with each other to drive the intermediate shaft by the driving shaft, a camshaft provided with two crank pins, a rigid link member positionably supported on the camshaft and positionable about the axis of the intermediate shaft providing a constant distance between the camshaft and the intermediate shaft, and one connecting rod, each between one crank pin of the intermediate shaft and one crank pin of the camshaft causing the camshaft to be driven by the intermediate shaft.

5. In an internal combustion engine a driving shaft, an intermediate shaft arranged parallel to the driving shaft and provided with two crank pins, a gear wheel on the driving shaf, a gear wheel on the intermediate shaft, said r wheels meshing with each other so as to cause the er 1 shaft to be driven by the intermediate shaft, a case encircling said gear wheels, said case being supported so as to be positionable about the axis of the driving shaft and serving as support of the intermediate shaft, a camshaft provided with two crank pins, a rigid link member positionably supported on the camshaft and positionable about the axis of the intermediate shaft providing a constant distance between the camshaft and the intermediate shaft, and one connecting rod each between one crank pin of the intermediate shaft and one crank pin of the camshaft so as to cause the camshaft to be driven by the intermediate shaft.

6. In an internal combustion engine an intermediate shaft arranged parallel to the driving shaft, a gear wheel on the driving shaft, a gear wheel on the intermediate shaft in operative engagement with said first-mentioned gear wheel, said gear wheels causing the intermediate shaft to be driven by the driving shaft, a case encircling said gear wheels, said case being supported so as to be positionable about the axis of the driving shaft and serving as support of the intermediate shaft, said gear wheels and said case constituting a pump for circulating a liquid within the internal combustion engine, a camshaft, a rigid link member positionably supported on the camshaft and positionable about the axis of the intermediate shaft and providing a constant distance between both said axes, and means for driving the camshaft by the intermediate shaft.

7. In an internal combustion engine the combination according to claim 6, wherein said gear wheels and said case serve as a pump for circulating the lubricating oil within the internal combustion engine.

8. In an internal combustion engine an engine block, comprising a crankcase, a cylinder block and a cylinder head, a crankshaft with an extension, an intermediate shaft arranged parallel to the crankshaft, said intermediate shaft consisting of two bearing journals, a gear wheel between the bearing journals and a crank pin each on the outside of the bearing journals, another gear wheel on said extension of the crankshaft, said gear wheels meshing with each other so as to drive the intermediate shaft by the crankshaft, a driving case encircling said gear wheels, said case being positionably supported on said extension of the crankshaft and containing the bearings for the journals of the intermediate shaft, said gear wheels and said case serving as a pump for circulating the lubricating oil within the internal combustion engine, a camshaft provided with two crank pins and a concentrio section between the crank pins, a rod one end of which is supported on said concentric section of the camshaft and positionable with its other on said driving case and providing a constant distance between the camshaft and the intermediate shaft, and one connecting rod each between one crank pin of the intermediate shaft and of the camshaft to drive the camshaft by the intermediate shaft.

References Cited in the file of this patent UNITED STATES PATENTS 2,596,410 Jordan May 13, 1952 FOREIGN PATENTS 26,264 Great Britain Nov. 27, 1907 215,900 Great Britain May 22, 1924 525,120 Great Britain Aug. 22, 1940 372,961 Germany Apr. 4, 1923 

